Fluid-dash-pot buffer device.



P. O. FURLQW. FLUID DASH POT BUFFER DEVICE. APPLICATION FILED 001. s, 1907,

986,378, Patented Mar. 7, 1911.

/ I g g amounts-z I mtoz m ew f [UN TED STATES PATENT oFFIoE.

lFLQYD G. FURLOW, OF MONTCLAIR, NEW JERSEY, ASSIGNOR TO OTIS ELEVATORCOM- PAINY, F JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

FLUID-DASH-PQT BUFFER DEVICE.

.? To all whom it may concern:

.Be it known that I, FLoYn C. FURLO a ,pitizen of the United States, residing in 'Montclair, in the county of Essex and State ofNew- Jersey, have invented a new and use .t'ul Improvement in Fluid-Dash-Pot Buffer )evices, of which the following is a specifi "cation.

v My invent-ion relates t'o saf'ety buffers for lo el evator s, and one of its objects is the pro-- wision of simple and etlioient, means for gradually retarding an elevator car inde pendently of its operating apparatus so as ,to, bring the car to rest gradually with mini- 1. 5: mum shock-or ar. I

- further object. of the inventionis the provision of means for resetting or returnto its initial position the buffer device up o-n the release therefrom of the moving '20 :parto1. the elevator which is arranged to 'gjbt brought into-engagement with a moving part oi the buffer device. v

Other objects of the invention will-appear hereinafterpthe novel combinations ofelentents, being set forth in the appended claims. ;In the" accompanying drawings, Figure 1 vr itihe application of my invention; Fig.2 is a -;.verti.oa%l sectional elevation of'one form of 3 my improved bufi'er vdevice including the -,restting, means therefor; and Fig. 3 is a view similar to Fig. 2, but showing a modi- ,.-fication. l .-I-n general, my invention comprises a 3 buffer device or shock absorber to overcome '-.%t1 1einertia of a movingbody in an elevator in; gradually stopping the same. In the drawing I. have shown the buffer device at the lower-limit oftravel of-an elevatorcar, 4 although obviously it maybe placed-in the path-of the counter-weight or in-the path of any other moving part which it is desired to stop gradually, Whether such part is in an system of other analogous apparax-Tn Fig. 1. two cushioning devices of the form shown in detail in Fig. 3-are shown at the lower limit of the elevator Well so as to beengaged by the elevator car as the same :0 approacl'ies its lower limit of travel, and by Speizification of Letters latent.

ep'resent'sfan elevator system illustratii'ig load to force the fluid outof through the exhaustpipe 15. l

Patented Mar. '7, 1911.

Application filed October 9, 1907. Serial No. 396.553.

elevator car 1 traveling along the usual.

guiderails (not shown). To the bottom of the car is securely attached the plunger 2 which is arranged to move up and down' freely in the main cylinder 18. The latter is supplied with fluid under pressure through the t-o-and-fro1n pipe 16 from the pressure supply pipe ll through the change valve 17. designates the discharge or exhaust )lpt.

l The operation of the ehangeyalve 17 is controlled by means of a hand lever in the car eoiiperating with the standing ropes 0, the sheave 111, the pinion 1'2- and the rack bar 13 in the well known manner The standing ropes 9 are fastened at 8 to the overhead beam :6. The cable 4 is-attaehed to the upper side of the car and extends upwardlyover the sheave 5. mounted .on the overhead beam 6 to the counterbalance weight- 7. The. counterweight partially balances the combined weight of the car and plunger. The cylinder 18 is closed at its lower end by a head 19 and when the caroperating lever 10 is moved in one direction or the other, the change valve 17 will. be

. to lift. the ear. or so as to cause the unbalanced weight of the, car and plunger and I p v the cyl nder Although in some n'ist-ances only one butfer. devicewould be sutlieient, it would be preferable in st-opping'an elevator car toemnloy a plurality of them. In this" instance 1 have shown two buffer devices 20in Fig; 1 at the lower limit of travel of the" elevator car.) and so placed in respect thereto that each will be engaged by the botton'io f the car near the lower limitofthe c ars travel.

Referring'now lo'Fig. 2 which shows the details of one form of my invention, 21 designates -a heavy compression spring loosely supported in a tube 22, and extending a short distance above the latter. The lower end of this tube is connectedby the coupling 23 to the upper end of the tube 25. This cou-.

pling is screw-threaded at its-ends to fit into I "the screw-threaded lowerendof the tube 22 andfthe screw-threaded upper end of the tube 25, the middle ortion of said'coupling being of substantial y the same diameter as the tubes. The lower end of the tube 25 is screw-threaded into the piston 26'which fits ,is an outer 'cylin er casing 34, the lower end of which fits. over the flange 32 and is provided with external screw threads to re ceive an internally threaded ring 35, secured to the support 33 by bolts 36; The upper end of the casing 34 is provided with a head pression springs serve to hold the tube 25- and parts carried thereby in their .upper- "down. h The cylinderBl is provided with large 37 which is firmly secured in position by means-of a ring 38 which is scr'ewrthreadedonto the upperend of the casing 34. The head 37 and the ring 38 are secured together by bolts 39. The head of the casing is provided with a central opening through which the tube 25 can slide freely, but without any lateral play, so that the tube 25 is guided in its vertical movements, and the piston head- 26 Within the cylinder. 34. is a series of helical springs 4O placed one above another and Above the upperinost spring 40 is placed a disk-or washer 42 separated by rings 41.

which bears against said spring. Above the disk42 is a ring orstop-collar 43 secured to .the tube 25 by screws 44. Thisring forms' a stop. or abutment for the disk 42, and also forms a stop to limit the upward movement of the tube 25 in the casing 34. The commost position as shown in'thr drawing, and

in thls position the springs 40 are preferably slightly compressed. When the buffer device is operated and the tube 25 carried" downwardly, the springs are compressed between the disk 42 which is carried down with .the tube, and the flange 32 on which the bot.-

The head 37 'of the 40 rests.

tom sprin the disk 42 are provided with casing an openings 45 for the passage of air to and 25 moves up and fromthe easing as the tube openings 47 near its top, and below said openings is a spirally arranged series of small holes 48. It WiIFbeTbseiVed that the openings 47 are comparatively large and the pitch of the spiral row. of holes is greatest near the top of the cylinder, and gradually diminishes toward the bottom of the cylinder; also, that the distance between succescontain only air, I

prevented from binding in the cylinder 31'.

from the top to the bottom of the cylinder.

The purpose of this arrangement will a pear more fully hereinafter. Obviously t e same result might beattained by making the spiral row of openings of uniform pitch throughout, and making the distance be tween adjacent openings greater near the top and less near the bottom. Or, the same result could be obtained by making the dis:

tanee between adjacent openings uniform throughout, and varying the pitch to a eater extent than is shown on the drawin s. Other arrangements of the openings might be adopted which would accomplish the same results.

The tube 31 and c linder 34 are filled with some suitable liquid such as water or oil, up to the top of the cylinder 31 or higher. While it may be feasible to use water or other liquid or even to have the cylinder prefer to employ oil, since it prevents rusting or corrosion, does not evaporate appreciably, and at the same timelu ricates all the moving parts. Fur thermore, there is no possibility of the oil freezing and thereby rendering the device inoperative.

The operation of the bufferdevice is as follows. As soon as the elevator car or other moving part desired tobe stopped gradually, strikes the spring 21, the sameis compressed and the tube 25 and the piston 26 started gradually downwardly. The spring 21 acts as a cushion for the tube or actuating device 25-and piston 26, and thus prevents them from receiving a sudden blow, and permits them to be started up. gradually. The oil.

contained'in the cylinder 31'is now forced to flowthrough the openings 47 and 48. During the initial movement the large openings 47 permit a free escape of the oil and the piston is restricted but little .in its movevator is due principally to the inertia which has to be overcome in quickly starting the moving parts of the buffer device- As the lower end of the piston 26 passes-below the openings 47, the escape of the oil is confined to the small openings 48, and the flow of oil from the cylinder is retarded. As the piston '26 continues to move downwardly, the rement, and the retarding effect on the eletardation to the flow of oil. gradually in creases by reason of the-gradually decreas ing number of openings 48 below the piston. The rate at which this retardation increases also increasesasy the piston moves down-.

'watdly, owing .to the gradually diminishing vertical distance between the openings. In other words, thelow'er'the piston is in the. cylinder, the more openin s 48 will be covered in a given length 0 travelbf the the oil under the piston has no outlet and the nature of the fiuid does not permit of compression since it is substantially; nouelastie.

It will be seen that. the butter device will effectual-1y operate to quickly and smoothly bring the elevator car to rest. The higher the speed of the carythe more powerful will be the reacting retarding efi'ect. It is a well known physical law that the resistance to the escape of a liquid through a restricted opening is substantially proportional to the square of thespeed with which it escapes. It is also well known that the power neces sary to -'overcome the momentum of a moving body in bringing it to rest within a certain length of travel is proportional to the square of its velocity. It follows from the application of these laws to the operation of the bufl'er device that the retarding effect of the openings 47 and of the restricted openings 48 will be directly proportional to the square of the speed of the pistonand therefore directly proportional to the power necessary to overcomethe momentum of the moving parts in bringing them to rest during the travel of the piston through the cylinder 31. Asa practical example, to make the application of these laws clear, let is be assumed that the piston is movingdownward ly with a velocity of 20 feet per second, that its lower end is just above the large openings 47, th-atthe weight of the moving parts is such that an upward force of 500 pounds on the piston is necessary to bring the parts to rest by the time the piston has reached its lower limit of travel, and that the size of the openings is such that a downward pressure of 500 pounds 011 the piston will be nee ..:sary to overcomethe retarding efi ect of the openings when the piston is moving with velocity of 20 feet per second. Then the upward pressure of the oil on the piston is'500 pounds, the amount needed toredufce its speed at the proper rate to bring it to rest at the bottom of the cylinder. I Comparing with this an example in which the speed of the piston is, doubled,or 40 feet per second,.with the parts in the same position, it will be seen that the upward pressure necessary to bring the parts to rest by the time the p1: .1 reaches its lower limit will now 'be quadrupled, or 2,000 pounds.

But the retarding effect of the oil which is now being forced through the openings 4-8 with double the velocity will also be quadrupled, or 2,000 pounds It will thus be seen that the retarding effect of the oil for any given speed of the piston will always be proportional to the power needed to over; come the momentum of the moving parts Within a given length of travel. By'nlakiug the openings of the proper sizet'or one. speed, they will operate equally well for any other speed and the great advantage of this over springs and other devices which effective only within narrow limits of speed,- is obvious. By the use of oilor other liquid the tendency of the elevator to rebound is also entirely removed.

It has been found in practice preferable to arrange enlarged openings 47 at the top and the openings 48 in a spiral series with the vertical distance between adjacent openings near the top of the cylinder greater than that between the openings near the bottom. By this arrangement the openings 48 are cut oil by the piston at a'imore nearly uniform rate than if they were uniformly spaced, owingto the gradually decreasing speed of the piston as it descends. In other words, the arrangement is such thatthe retarding influence of the escaping oil is substantially constant throughout the travel of the piston 20, but proportional. to the momentum of the moving body to be gradually stopped. \Vhen such body first strikes the buffer device the flow of the oil should be comparatively t'ree, but the resistance to movement or the pressure produced on the oil the same as when the momentum is beingsubsequently overcome. That is, the back pressure of the oil in overcoming the momentum. is substantially constant throughout the travel of the piston 26.

As soon as the elevator car or the moving part which. has engaged the spring 21, is moved away from the butter device, the piston and attached mechanism is forced up I above the cylinder 31, the springs 410 being still slightly under compression. As the piston moves upwardly the oil flows back into the cylinder and the hufier device is again -ready for operation.

Rel erring'now to Fig. 3 which shows a somewhat modified construction,- the compression spring 21 is surmounted by a. rubber cushion 50 which helps to deaden the blow of the elevator car or other moving part when it strikes the butter. The spring 21 is loosely mounted in a'short tube or inverted cap 22 secured to the top of a tubular piston rod 25. The lower end, of the piston rod 25 is screw-threaded to receive a collar 51 bolted onto a piston 42. The piston rod. is provided with a series of perforations 52 near its lower end. A tubular casingfii similar tothe casing 3l is screw-threaded into a supportor standard 33- which is provided with holes for belts or other fastening means to securely hold the buffer device in proper venti on.

position. The bottom of the casing 34: is provided with .a'central recess 54 which is screw-threaded to receive thelower screw threaded end of the. tube 55. Within the tube 55 is a hollow rod- 56 extending from the bottom of the tube 55.np through a central opening in the piston 42 and into the piston rod 25. Surrounding the rod 56 is a coil spring 57 which rests on the tube 55 and forms a resilient stop for the piston 42' and parts carried thereby. The hollow rod 56 is provided with a series of graduated openings 58 extending from near the top of the rod to a point a short distance above the top of the tube 55. These openings are gradually diminishing diameters from the top one, which is large enough to offer little resistance to the flow of oil therethrough, to the lowest opening which will allow the oil to pass only very slowly.

A coil spring 40 yieldingly holds the piston 42 in its upper position and returns it to such position after the buffer device has operated. Bolted to the upper end of the easing 34: is a hollow cap 60, which forms a liquid receptacle. This cap surrounds the hollow piston rod 25 and is provided with a stu'fiing box 61 to guide the tube 25 and prevent escape of the liquid. The receptacle taken as a whole and including the cylinder 34 and cap 60 is filled with oil or other liquid. The hollow rod 56 is therefore also filled. The operation is similar to that of the construction shown in Fig. 2. lVhen the piston commences its downward move ment, the oil beneath it will be forced into the hollow rod 56, the oil already in the rod being forced out through the top of the rod or the openings 58 which are above the piston, and through the openings 52 into the space above the piston. This circulation of the oil continues as the piston descends, the restriction to the flow 'of oil gradually becoming greater as the number and size of the openings 58 below the piston diminish.

'When the piston has covered the last opening 58, it will be brought to rest, owing to the incompressible nature of the oil, unless there isleakage between the piston 42 and the cylinder'frla or between the piston and the rod 56, in which case it may move far enough to compress the spring 57, and will then be brought to an absolute stop. The spring 57 willact. as a butler tostop the car without any jar in case it is not brought to a complete stop by the retarding effect of the oil.

lVhile I have described my device in connection with an elevator system, there are doubtless other uses to which my invention couldbe put. to great advantage without in- I have shown different forms of construction embodying my invention, but it might be embodied in various other forms, and it is obvious that various changes in details and arrangement of parts might be made by those skilled in the art without departing from the spiritand scope of the invention. I, therefore, desire not to be limitedwto the precise constructions and arrangements of parts disclosed.

What I claim as new and desire to secure by LettersPatent of the United States is 1. In an elevator buffer, the combination with a receptacle, of a tubular member within the receptacle provided with a series of perforations, and a piston having sliding contact with said member, and substantially unobstructed during its initial movement.

2. In. an elevator buifer, the combination with a receptacle, of a. cylinder provided with perforations communicating with the interior of the receptacle, and a piston having sliding contact with said member and movable past said perforations successively, said perforations being positioned to per-- mil; a rapid acceleration of said piston fromits initial position.

In an elevator buffer, the combination with a receptacle for containing a liquid, of a hollow member within the receptacle open at one end to atmospheric pressure and provided with a series of lateral openings, and a movable member provided with means for forcing, a liquid through said lateral open= ings, and gradually reducing the number of openings through which the liquid may pass. I

4. In an elevator butter, the-combination with a receptacle for containing a liquid, of a tube within the receptacle open at one end and also provided with aseries of lateral series of lateral openings, and a piston in sliding engagement with the cylinder, the

said parts being arranged to permit a free flow of the liquid from in frontof the pistonduring its initial inward movement.

(3. In an elevator buffer, the combination with a receptacle for containing liquid, of a cylinder within the receptacle open at one end and also formed with lateral openings near said er of a size to permit a tree passage of the liquid, and a series of smaller openings between said first openings and the other end of the cylinder, and a piston movable in engagement with the cylinder.

' 7. In an elevator buiier, the combination of a receptacle for containing liquid, a cylinder within the; receptacle formed with lateral openings, and a piston in slidable engagement with the cylinder, the liquid on opposite sides of said piston having unob; structed communication during the inititl" inward travel. of the piston.

ins 0 8. In an elevator buffer, the combination with a receptacle, ot' a tube within the receptacle open at one end. and formed with. a series of lateral openings at successively diminishing distances apart as measured longitudinally of. the tube and from said end,

and a piston in sliding'engagement with the tubel V 9. In an elevator buffer, the combination with a rcceptaclefor containing liquid, of a tube within the receptacle open atone end and formed with graduated lateral openings,

and a piston in slidable engagement with the tube and unobstructed during its initial inward movement.

10, I11 an elevator buffer, the combination with a receptacle for containing a liquid, of a --tube within the receptacle open at one end out of the cylinder, a resilient butter member mounted on said actuating device, and

. a stop or abutment 011 said actuating device, and means engaging said stop for holdmg said piston normally in a predetermined position and for automatically resetting the same after being actuated and released. r

12. In an elevator buffer, the combinat on wlth a fluid butler dash-pot comprising a piston and piston rod, of a plurality of-springs arranged in series, and a connection between one of the springs and the dash-pot piston rod to effect a restoration of the piston to normal position by the action of said springs.

13. In an elevator buffer, the combination with a' hollow member open at the top, laterally perforated and closed at the bot-tom, of a piston movable in said hollow member, an actuating rod connected to said piston,

and a spring for restoring said piston to initial position and holding it there While no pressure is exerted on said actuating rod, the latter engagii'ig said spring.

14. In an elevator butler, the combination with a closed receptacle, of a tube within Paid receptacle and rigidly connected? thereto, said inner tube having lateral perforations and being entirely closed at and near the bottom and open at the top, a piston movable within said inner tube, a piston rod, and a spring within said receptacle for holding said piston and piston rod in initial position.

15. In an elevator butler, the combination. with a receptacle, of a tube within the receptacle, a piston slidable in said tube,

a piston rod, and a spring interposed between the tube and receptacle and acting on said piston rod.

16. in an elevator butler device, the con:- binalion with a hollow member open at the top, laterally perforated and closed at the bottom, of a piston movable in said hollow member, an actuating rod connected to said piston, and a spring for returning said piston to initial position and holding it there while no pressure is exerted on said actuating rod, the said spring being located outside of said hollow member.

17. In an elevator buffer device, the combination of a closed receptacle, a tube within said receptacle and rigidly connected thereto, said inner tube having lateral perforations and being entirely closed at and near the bottom and open at its upper end, a piston movable within said inner tube, a piston rod, and a spring within said receptacle tor holding said piston and piston rod in initial position, said spring being located outside of and surrounding said innor lube.

In testimony whereof, I have Signed my name to this specification in the presence of two subscribing witnesses.

FLOYD C. FURLOW.

WVitnesses:

IN. W Lioi'rrmrn, V. II. BRADY. 

